Taxonomy and Phylogeny of Neosiphonia japonica (Rhodomelaceae,Rhodophyta) Based on rbcL and cpeA/B Gene Sequences

Abstract

Neosiphonia M.S. Kim et I.K. Lee is a rhodomelacean red algal genus that is commonly encountered in the intertidal zone of temperate waters in the world. The genus Neosiphonia, which was established based on species previously named under the genus Polysiphonia, is well distinguished by procarps bearing a three-celled carpogonial branches, spermatangial branches arising from a branch of the trichoblasts, and tetrasporangia arranged in spiral series (Kim and Lee 1999). The phylogenetic difference of Neosiphonia from Polysiphonia is clearly shown by both cladistic analyses of morphological features and phylogenetic analyses of nuclear ribosomal small subunit (SSU) region sequences (Choi et al. 2001). Recently, Neosiphonia is found in Malaysia (Masuda et al. 2001; Tani et al. 2003), Vietnam (Abbott et al. 2002), Brazil (Guimaraes et al. 2004), Hawaii (Kim and Abbott 2006), and Japan as well as Korea (Kim 2005). To date, 22 species previously placed in Polysiphonia have been transferred into Neosiphonia and 1 new species reported. Neosiphonia japonica (Harvey) M.S. Kim et I.K. Lee was originally described from Hakodate, Hokkaido, Japan, as Polysiphonia japonica by Harvey (1856). The species has a bush-like habit, four pericental cells, cortication on axes, numerous branches, and three-celled carpogonial branches on females. The thalli occur commonly as epiphytes on other seaweeds from Korea (Kim 1995), Japan (Yoshida 1998), China (Tseng 1984), and Pacific Russia (Perestenko 1994). Despite studies on the morphology (Yoon 1986; Kudo and Masuda 1986; Kim 1995), life history (Kudo and Masuda 1986), lectotypification (Masuda et al. 1995), and distribution (Kim 1995), the taxonomy of N. japonica is still problematic. Kudo and Masuda (1986) reported that N. japonica (as Polysiphonia japonica) is very similar to N. harlandii (Harvey) M.S. Kim et I.K. Lee, N. decumbens (Segi) M.S. Kim et I.K. Lee, and P. akkeshiensis Segi. Yoon (1986) also concluded N. savatieri (Hariot) M.S. Kim et I.K. Lee, P. forfex Harvey and N. teradomariensis (Noda) M.S. Kim et I.K. Lee as varieties of N. japonica, based on the number of pericentral cells and the presence or absence of cortication at the base. Recently, McIvor et al. (2001) proposed that N. japonica, together with P. akkeshiensis Segi, P. acuminata N.L. Gardner and P. strictissima J.D. Hooker & Harvey were conspecific with N. harveyi (J. Bailey) M.S. Kim, H.G. Choi, Guiry & Algae Volume 21(3): 287-294, 2006